Battery Water Question - Interesting Observation

Not a problem, not an issue. While ideally you might think that your positive lead would come off the lower left, and your negative off the upper right in reality it does not matter. If through some freak of resistance power is drawn from a closer battery, the other battery in parallel will then have more power and be dominant. They will remain the same. The water issue could be coming from anything else, but not your electrical loading of the wires.